On Wed Apr 20 10:00:21 2016, muks wrote:
> There's a race in the adaptive rwlock implementation in read and
> update of rwl->spins.

The new code seems to use ISC_PLATFORM_BUSYWAITNOP which seems to be defined as "rep; nop" for x86 and x86_64.

rep is an instruction prefix that repeats the next instruction ecx times, decrementing ecx at each step. So ecx ought to be set to some deterministic value for it (what is its value here?). Also it clobbers ecx here.. is that fine?